MOM6 tidal momentum forcing

[dougiesquire]

Tidal momentum forcing (MOM6 parameter TIDES and associated parameters) has been disabled in our 0.25 deg configuration, but the changes were not carried across to our 1 deg configurations. Was this deliberate? @minghangli-uni, @aekiss?

[minghangli-uni]

Yes, for the 025deg, the model can resolve tidal and internal wave dynamics. 1deg is too coarse to resolve internal tides explicitly, so it relies on parameterisations to represent the missing mixing associated with tides.

[dougiesquire]

I'm confused sorry. How are there tides in the 0.25deg config with TIDES=False?

[minghangli-uni]

My understanding is at this eddy-permitting resolution along with the topo, tides begin to appear natually without parameterisation.

[aekiss]

As discussed in today's OSIT catchup, we don't want explicit tides in any of our default global configs (although at 0.1° and higher some users may wish to switch it on). So we don't want tidal forcing.

Instead, we need to parameterise the impact that the tide would have had. In OM2 we have vertical mixing and viscosity due to both barotropic and internal tides - see sec 3.2.6 in https://cosima.org.au/wp-content/uploads/2025/01/ACCESS-OM2-1-025-010deg-2025-01-24-7be8a1c.pdf

[aekiss]

see #176 (comment)

[aekiss]

Are we still missing the external input data for averaged tidal flow amplitudes (tideamp.nc)? It's not in /g/data/vk83/experiments/inputs/access-om3

[dougiesquire]

Are we still missing the external input data for averaged tidal flow amplitudes (tideamp.nc)? It's not in /g/data/vk83/experiments/inputs/access-om3

I've obviously been away, but I don't think there's been any work on this since #176. INT_TIDE_DISSIPATION and READ_TIDEAMP are both False in all our configurations.

[aekiss]

ok, that will need to be fixed at some point

[dougiesquire]

Ta. I'll open an issue

[dougiesquire]

Closing as tidal forcing is now disabled in dev- branches :

1deg_ryf: ACCESS-NRI/access-om3-configs#181
1deg_iaf: ACCESS-NRI/access-om3-configs#184
1deg_ryf_wombatlite: ACCESS-NRI/access-om3-configs#185
025deg_ryf: ACCESS-NRI/access-om3-configs#186

And will be captured in #283 and #284